
Really? The Ottomans were much more authoritarian. Rulers of Christian nations like Constantin Brancoveanu are proof of that (his 5 sons were all beheaded in front of him, after each of them refused to convert to Islam, then he was beheaded himself, as he refused and claimed Christ as his saviour, and his head was thrown in the sea). That's just to give an image about how barbaric the Ottomans were. Oh, they are also the ones who burned hundreds of churches in Wallachia to the ground (which is the reason why stone churches appeared here) and forbade painting Christian religious symbols on anything. Sure, how very tolerant of them.
I find it amazing how other Europeans try to convince us that the past was a piece of cake for us and the Christians are the true, complete and only evil of the world.
Not that I dispute that particular piece of history. Nor do I think the Ottomans should somehow be awarded a clean bill on the curelty charge. However...
This is a piece of cruelty against the ruling elite. Why is what befalls that particular segment of society any particular cause for outrage? I'm not saying there might not be, but that it's kind of an incomplete incident, unless it's followed up by supporting information about how the Ottomans ran these conquered lands I think.
And besides, they were royalty in an age where the expectation among people of power and influence involved in high stakes politics was that if you fail, you die. Risk-less authority and leadership is a very modern notion. Kings in those days knew their lives were at stake all the time.
I also doubt king Constantin and his sons found their end too outrageous. Clearly a great misfortune for themselves, and their people, a sad end in all manner of ways, but not a particlarily cruel one.
Because being given a choice and a quick beheading, if you turn it down, by the standards of the time WAS lenient. We're not talking hung, taken down, resiscitated, disemboweled while conscious, to see your innards burned before your eyes, and THEN beheded.
Or dismembering by being pulled apart by four horses. Or simply your average run of the mill having all your limbes broken by the wheel before beheading. Or impaling. All of which western European Christian monarchs were won't to, and definately not just to rival royalty.
Beheading WAS lenient in general. That's why the sword was reserved for nobles and royalty in western Europe as the method of excution. Everybody expected to die more or less at the drop of a hat. The manner of your death was then a closely guarded privilege. If you really wanted to punish a rebel noble, or failed princeling, you hanged them, to add insult to injury. Or you did what Henry the VIII of England would do when in a nasty mood; appoint the newbie exceutioner's apprentice to make the chop, knowing the overwhelming odds of it turning out as a very messy exceution indeed. If the Sultan's executioner dispatched Constantin and his sons in six swift strokes, by the notions of the day, he was at least playing by the rules of decency in these matters.
For barbaric warfare, you could for instance read up on what Swedes and Danes did to each other in their endless 17th c. wars. Those wars were pure hate. If the Swedes found any civilians while invading Danish territory, they unceremoniously hacked their heads off. And vice versa. That's cruel. Do it to a defeated enemy monarch, being given a choice (crappy one but still), maybe not so much.
Or the French 13th c. medieval low intensity feuds between barons being conducted through economic warfare, meaning you catch as many serfs and peasants of the rival's you can, and then you hew off their feet. It usually left them alive, but relatively unproductive so they would form a drain on the local community's resources. That's cruel.
Afaik, similar things are perfectly possible to find in the Ottoman conflict with the various Christian kingdoms of the Balkans. It's just that it's a bit hard to actually prove that the Ottomans were particularily terrible, by comparison. I mean, the French fought a purely internal Christian religious civil war in the 16th c., where the dead counted in the millions, and a lot of them went in very cruel ways. I wouldn't presume the Balkans were necessarly better, but neither that they were worse.